1. Field of the Invention
The present invention relates to a technology for calculating importance of data.
2. Description of the Related Art
There are known technologies for calculating the importance of data.
For example, Japanese Patent Application Laid-open No. 2002-342379 discloses a technology for ranking the popularity of documents. According to the conventional technology, in addition to popularity obtained from document usage information based on similarity to a search keyword and a reference relation between documents, an expected value of future popularity is taken into account. Thus, accurate ranking can be achieved regardless of biased information even for a document with little information.
Japanese Patent Application Laid-open No. 2001-290843 discloses a document retrieval device that searches for document data from a document data group having a link relation. The document retrieval device weights the link relation, imparts link importance to the document data, and accesses the document data based on the link importance.
Japanese Patent Application Laid-open No. 2003-271653 discloses a technology in which documents in data are stored in association with an index indicating importance thereof. The documents are displayed in a list in order of the importance upon receipt of a request from a user. The importance of a document is increased when the document is requested, while the importance is reduced as the document is left unrequested.
However, in the technology disclosed in Japanese Patent Application Laid-open No. 2002-342379, only the document usage information is used, and therefore, it is not clear that the reader of the document has considered the document is useful after reading it.
With the document retrieval device disclosed in Japanese Patent Application Laid-open No. 2001-290843, the importance is determined based on the link relation. Therefore, the document retrieval device cannot be applied to a group of documents without links, i.e., those not linked to one another, such as documents referred to only within an office.
According to the technology disclosed in Japanese Patent Application Laid-open No. 2003-271653, only information on browse is used to calculate importance of a document. Therefore, it cannot be determined whether the reader has considered the document is important.